whatis
is almost identical to
apropos
(
50.2
)
,
but it requires a
command name as an
argument - rather than an arbitrary string.
Why is this useful?
Well, let's say you forget what
cat
does.
On my system,
apropos cat
gives you several screenfuls
of output.
You may not want to read the entire manual page.
But
whatis cat
gives you a nice one-line summary:

%
whatis cat
cat (1V) - concatenate and display

If you're using the
apropos
fake-out we discussed in article
50.3
,
you can simulate
whatis
with an
alias (
10.3
)
or
shell function (
10.9
)
: